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Kirk and Scotty's lie

30 September 1996

The Physics of Star Trek

Cosmology for many years was viewed as tantamount to science fiction by many scientists; indeed, this situation has hardly changed at certain prestigious academic institutions. However, there is no doubt that for the vast majority of scientists, cosmology has become a respected and solid discipline. Rarely a month elapses without the report of new discoveries at the frontier of the observable universe. Moreover, once the physicists entered the field of cosmology in full force during the 1980s, its previous incarnation as a realm of mathematically erudite but largely irrelevant toy universes became a pale shadow of the new cosmology. This is characterised by use of the very early universe, with its extremes of density and temperature, as a relatively inexpensive laboratory for high energy physics. Scores of elementary particle physicists, tiring of working in ever-larger collaborations on ever-larger experiments at ever-more costly particle accelerators, have streamed into the emerging field of particle astrophysics, to use the gift of cosmology as a hunting licence for exotic matter.

Cosmology tells us that 90 or even 99 per cent of the universe, consists of dark matter, yet we have little knowledge of its nature. Perhaps the dark matter consists of weakly interacting particles, that stream unimpeded through our bodies as the earth and sun orbit the Milky Way galaxy. Cosmologists tell us that the dark matter might alternatively consist of black holes, created by catastrophically large homogeneities in the very early universe. Such black holes would have a mass comparable to that of the sun and a size of a kilometre or two. The nearest of them may lurk a mere few light years from us, no further than the nearest stars.

All of these possibilities, from exotic particles to black holes, are solidly based on conservative speculations that follow directly from astronomical measurements. Dark matter is mainstream cosmology. There are even cosmologists of a more mathematical bent, and somewhat removed from the murky world of astrophysicists, who are hard at work designing time machines which utilise wormholes, and that work in principle if not in practice. Wormholes are tunnels through space and time that are not forbidden by the theory of gravity. "Anything that can exist must exist" is a common precept in physics. If so, time machines can be made from wormholes. The greatest worry has been dubbed the matricide paradox: suppose an intrepid adventurer went back in time and murdered his mother. Not to worry, quantum uncertainty comes to the rescue, and any murder attempt would necessarily fail. Concepts that verge on science fiction are the very essence of modern cosmology.

It is consequently not surprising that the best modern science fiction borrows heavily from cosmology. Indeed, the classical science fiction writers such as Jules Verne and H. G. Wells, foresaw various developments in cosmology and astronomy. Nowadays television viewing has largely overtaken reading as a form of entertainment and popular culture. The Star Trek television series includes the very best of science fiction, and still manages to succeed as mass entertainment. Science fiction is more widely watched than read as a consequence of the Star Trek series. Star Trek succeeds in part because it tries to make the stories convincing. The level is more that of pseudoscience, and occasionally science babble, rather than true science, but this is not necessarily doing science a disservice. The culture of science, its language and jargon, deserve to be more broadly disseminated. For far too long have we had the comic strip view of the evil scientist clad in a white coat, resurrecting Frankenstein again and again. I find it a pleasure, as a practising scientist who grew up on such comic strips, to see this image supplanted by practitioners of galactic travel at superlight speed, of time warps, of bodily teleportation and the like. Indeed these phenomena are no stranger than those recently encountered by readers of the serious British newspapers in reports of the experiments of a biologist who believes that dogs can predict the imminent arrivals of their masters or mistresses. No doubt the dogs have wormholes in their kennels.

The Physics of Star Trek is a delightful attempt by astrophysicist Lawrence Krauss to assess what is possible and what is not among the many themes developed by the Star Trek writers. Space and time travel are issues that Krauss tackles without hesitation. He points out that traversing the galaxy within the duration of a Star Trek episode would require wholly destructive accelerations that no spaceship nor its occupants could conceivably survive. Capture a wormhole, however, and one can use the geometry of space to accomplish what physical travel fails to do. Without moving an inch, or at least no further than a step into the wormhole, one can traverse the entire galaxy or even the universe. Moreover, one can emerge in the future, or in the past, or even, if one is unlucky, in another universe. Trapping the wormhole is not easy, as Krauss explains: to keep it open requires immense stresses that are beyond our experience, but not beyond our comprehension. Taming the wormhole is more difficult, and this is amply seen in the Star Trek episodes that feature unexpected encounters with wormholes and related phenomena.

Transporter beams are an impossibility. It is beyond the abilities of the largest imaginable computers to reassemble our molecular patterns. Further, the issue of our less corporeal attributes such as memory and emotion is ignored. Even if our space travellers of a future era were able to overcome these hurdles, transporting Captain James T. Kirk instantaneously to the surface of a planet light years away would require a telescope with the ability to resolve atomic dimensions. Krauss argues that this would require a telescope on the starship Enterprise of 50,000 kilometres diameter, but is unaware that atmospheric seeing, which is responsible for the twinkling of stars, makes such an exercise pointless. Other minor quibbles include the erroneous statement that the oldest objects in the galaxy, globular clusters, consist of thousands of stars, and the apparent unawareness of the author about the discovery of dark matter in the form of massive objects in our halo, first announced in 1993.

The Physics of Star Trek is an excellent guide to the Star Trek universe for the amateur scientist. There is not always a clear distinction between what is possible and what is not. But Krauss's heart is in the right place, and he has produced a book that will surely help the cause of science rather than hinder it. Star Trek is part of our popular culture. Teenagers quote such perennial lines as "Beam me up Scotty" and debate the merits of time travel after any memory of lines from Shakespeare or Keats has long since faded. And who is out there, in this age of science and high technology, that dares to challenge them?

Joseph Silk is professor of astronomy and physics, University of California, Berkeley.